Post on 26-Feb-2022
UK/I 0343A
STEPHEN CUTMORE BSc(Hons), MArborA
PRO3755
Arboricultural & Ecological Services
S U R V E Y S , I N S P E C T I O N S , R E P O R T S
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
BUILDING PLOT
(BETWEEN ‘Y CULFOR’ AND ‘CAE PYSGODLAN’)
BANGOR ROAD
CAERNARFON
GWYNEDD
LL55 1LN
ADVANCED TREE INSPECTION
UTILISING THE PICUS SONIC TOMOGRAPH AND
IML PD-400 RESISTOGRAPH
Report by:
Stephen Cutmore BSc (Hons), MArborA I.S.A. Certified Arborist U/I-0343A,
I.S.A Tree Risk Assessment Qualified
Client Kyra Beguiristan
Planning Authority Gwynedd County Council
Date of Survey 21 April 2017
Grid Reference SH488 639
Reference 042017/ATI-KB
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
TABLE OF CONTENTS
1.0 SUMMARY 3
2.0 INTRODUCTION 4
2.1 Brief
2.2 Purpose of this report
2.3 Scope of this report
2.4 Relevant background information 5
2.5 Tree identification and location
2.6 Qualifications
2.7 Copyright
3.0 DATA COLLECTION 5
3.1 Site visit
3.2 Site description
3.3 Methodology 6
3.4 Results 7
4.0 APPRAISAL
4.1 Analysis of IML PD-400 Resistograph drillings 8
5.0 CONCLUSIONS 9
6.0 RECOMMENDATIONS 9
APPENDICES
APPENDIX 1 – Site plan 10
APPENDIX 2 – Picus Sonic Tomographs 11
APPENDIX 3 – Resistograph drill readings 13
APPENDIX 4 - Photographs 21
APPENDIX 5 – Bibliography 22
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 2 of 36
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
1.0 SUMMARY
An advanced inspection was carried out on the three Beech trees (T1, 8 & 9), using hi-tech
decay detection equipment. The Picus Sonic Tomograph (SoT) utilises ultra-sonic
soundwaves to assess the internal condition of the trunk cross-section being tested.
The PD-400 Resistograph micro-drill drills a narrow diameter drilling needle into the wood,
whilst recording the resistance of the wood against the cutting tip. High resistance indicates
healthy wood, low resistance indicates defects in the wood (decay, cracks etc.).
Various researchers have devised mathematical equations regarding the safety factors of
trees, based on scientific evidence that a hollowing tree can remain stable providing that there
is a residual wall of solid, healthy wood around the periphery of the trunk. A ratio of
residual wall thickness to the radius (t/R) of 0.3 is given as a rough guideline for safety, for
tall trees with a full canopy exposed to wind-loading [Mattheck, Bethge and Weber, 2015].
The SoT showed a central cavity in the base of Beech T1. The PD-400 drillings confirmed a
central cavity and indicated that the 1/3 radius safety margin has been breached at MP2 and
MP7. The conclusion is that the tree is in a critical condition. The advanced decay/cavity
will likely increase in intensity and extent over the next few years. The tree is posing an
increasingly high risk to the high value targets in the danger zone (people, vehicles using
Bangor Road). The recommendation is to section-fell the tree to ground level for safety
reasons.
The PD-400 drillings for Beech (T8) confirmed the 1/3 radius safety margin remains intact at
this time. The conclusion is that the tree can be safely retained at this time. The
recommendation is to crown reduce the tree by 25%.
The SoT indicated an open cavity in the east of the trunk base of Beech T9. The narrow
transition from solid wood to decay indicates a strong defensive barrier is present in the
wood. The 1/3R safety margin remains intact at this time. The defensive barrier is inhibiting
the spread of the fungus into the rest of the trunk cross-section at this time. The conclusion is
that the tree can be safely retained at this time. The recommendation is to crown reduce the
tree by 25%.
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 3 of 36
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
2.0 INTRODUCTION
2.1 Brief
Stephen Cutmore BSc (Hons), MArborA, was instructed by Kyra Beguiristan, in the form of a
telephone conversation on 18 April 2017, to carry out an advanced tree inspection of three
mature Beech trees on the building plot, (between ‘Y Culfor’ and ‘Cae Pysgodlan’), Bangor
Road, Caernarfon, Gwynedd, LL55 1LN.
The definition of the assignment was to:
1. Carry out an Advanced Tree Inspection of the three Beech trees, utilising hi-tech decay
detection tools.
2. Assess the condition of the trees.
3. Provide a report with management options.
2.2 Purpose of this report
The purpose of this report is to advise you of the results of the parts 1-2 of the assignment.
These results are set forth in the Conclusions section, following. This report describes the
field conditions as found and interpreted.
2.3 Scope of report
Date of consultation.
The field examination was made on 21 April 2017, and observations and conclusions are as
of that date.
Limit of scope.
This is solely an Arboricultural Report and cannot comment on topics outside this discipline.
If additional advice is required, it is strongly recommended that other professionals are
consulted e.g. Structural Engineers or Surveyors.
1) information contained in this report covers only those trees that were examined and
reflects the condition of those trees at the time of the inspection: 2) the inspection is limited
to visual examination of the subject tree from ground level only and 3) specialist hi-tech
equipment was utilised to assess the internal condition of some of the trees.
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 4 of 36
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
2.4 Relevant background information
During a recent tree survey, three mature Beech trees were identified as having decay present
in the trunks. If there is significant decay present in the Beech trees, they could pose a high
risk to public safety.
2.5 Tree identification and location
The subject trees were identified in my previous report [Tree Condition Survey to BS5837
(2012), dated 6 January 2017] as T1, T8 and T9. The trees are located within the boundaries
of the building plot, (between ‘Y Culfor’ and ‘Cae Pysgodlan’), Bangor Road, Caernarfon,
Gwynedd, LL55 1LN. Beech tree (T1) is located on the south-east boundary adjacent to the
busy A487 Bangor Road. The other two trees (T8 & T9) are located near to the north-west
boundary of the site, within falling distance of the neighbouring residential property located
to the north-east. The locations of the trees are shown on the site plan, attached as Appendix
1.
2.6 Qualifications
Stephen Cutmore has over thirty years’ experience in the arboricultural and forestry industry
as a contractor and has over twenty years’ experience as an arboricultural consultant.
Stephen holds a BSc (Hons) in Arboriculture & Urban Forestry and is a Certified Arborist
UK/I-0343 [International Society of Arboriculture]. Stephen is a Professional Member of the
Arboricultural Association (MArborA) and is also an Associate Member of the Institute of
Chartered Foresters, currently working through the Institute’s Professional Membership Entry
towards Chartered status. Stephen has attended three Masterclasses for the Picus and one
Masterclass for the Resistograph, run by the UK distributors, Sorbus International and has
specialist knowledge in advanced tree inspections utilising hi-tech decay detection
equipment.
2.7 Copyright
Copyright © 2017 by Stephen Cutmore. All rights reserved. This report or any parts thereof
may not be reproduced without the prior written permission of the author.
3.0 DATA COLLECTION
3.1 Site visit
A site visit was made on the morning of 21 April 2017. The weather was dry and sunny.
There were no limiting factors to the inspection.
3.2 Site Description
The site is an unmanaged pasture field, with predominantly mature age class broadleaved
trees located around the boundaries. Residential properties are located either side of the plot
and a horse paddock field is adjacent to the north-west boundary. The A487 Bangor Road is
adjacent to the south-east boundary.
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 5 of 36
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
3.3 Methodology
An advanced inspection of the three Beech trees, utilising specialist decay detection
equipment, was carried out.
The data obtained in the advanced inspections was analysed and the condition of the trees
were assessed.
Picus Sonic Tomograph
Two Beech trees (T1 and T9) were tested with the Picus Sonic Tomograph (non-invasive
technique) to assess the internal condition of the trunks near the base. The Picus Sonic
Tomograph works on the basis that solid wood is a better sound transmitter than decayed
wood. Sonic sensors were strategically spaced around the circumference of the trees, to detect
stress-waves induced by manual impact and propagated through the wood. Electronic
callipers were used to accurately plot the positions of the sensors. A computer analysed the
data and generated a two-dimensional colour sonic tomograph (SoT) of the cross-section,
detailing areas of solid wood, decay and cavities within the tree. On the tomograph, brown
colours indicate solid, healthy wood. The colours green, violet and blue indicate increasing
degrades of decay. The SoT tomographs are included as Figures 1 and 2 and also as
Appendix 2.
IML PD-400 Resistograph microdrill
Following the Picus Sonic Tomograph assessment, a further assessment of Beech T1 was
made near the base, utilising the IML PD-400 Resistograph. An inspection was also carried
out on Beech (T8), which had an open cavity extending some distance up the north-east
trunk. The PD-400 Resistograph is a precision tool, used to accurately assess the internal
condition of trees. The device has a narrow 2mm diameter drilling needle with a maximum
drilling length of 400mm. As the drilling needle is drilled into the wood at a constant
velocity, the resistance of the wood against the tip of the drill-bit is digitally recorded. High
resistance indicates solid, healthy wood. Low resistance indicates defects in the form of
decayed wood, cavities, cracks, etc.
Four drill tests were carried out around the trunk of Beech (T1) at 20cm height and one drill
test at 10cm height. Three drillings were carried out on the north-east trunk of Beech (T8) at
4m height. The Resistograph readings are included as Appendix 3.
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 6 of 36
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
3.4 Results
Picus Sonic Tomograph
Beech T1
Figure 1: SoT of Beech T1 at 20cm above ground.
The SoT indicates a decay cavity (blue colour) across the centre of the trunk and extending
towards the south side of the trunk [Measuring Point 7], with associated advanced decay
(violet colour) and early-stage decay (green colour). Solid wood (brown colour) is shown
around the trunk periphery. The light brown colour indicates a reduction in the sonic
velocity, where a fungus may have inoculated the wood, but not yet degraded the cell walls of
the wood cells. The superimposed red line indicates the 1/3 radius safety margin.
Beech T9
Figure 2: SoT of Beech T2 at 10cm above ground.
The SoT indicates an open decay cavity on the east of the trunk [MP9-10]. The tomograph
indicates a small amount of advanced decay and early-stage decay around the inner margins
of the cavity. The rest of the trunk cross-section is shown as solid wood. The light brown
colour indicates a reduction in the sonic velocity, where the fungus has inoculated the wood,
but not yet degraded the cell walls of the wood cells. The superimposed red line indicates the
1/3 radius safety margin.
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 7 of 36
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
3.4 Results (continued)
IML PD-400 Resistograph
Beech T1
Test #1(MP2): The drilling shows sound wood until 17.3cm before encountering advanced
decay/cavity.
Test #2(MP5-6): The drilling shows sound wood until 30cm before encountering advanced
decay/cavity.
Test #3(MP7): The drilling shows sound wood until 18.9cm before encountering advanced
decay/cavity.
Test #4(MP9-10): The drilling shows sound wood until 30.7cm before encountering
advanced decay/cavity.
Test #5(MP5-6) at 10cm above ground: The drilling shows sound wood until 25.7cm before
encountering advanced decay/cavity.
Beech T8
Test #6: The drilling shows sound wood until 24.1cm before the needle automatically
retracted when constant pressure on the handle was interrupted.
Test #7: The drilling shows sound wood until 30.7cm before the needle automatically
retracted when constant pressure on the handle was interrupted.
Test #8: The drilling shows sound wood until 35.1cm before encountering advanced
decay/cavity.
4.0 APPRAISAL
4.1 Analysis of IML PD-400 Resistograph drillings
Various researchers have devised mathematical equations regarding the safety factors of
trees, based on scientific evidence that a hollowing tree can remain stable providing that there
is a residual wall of solid, healthy wood around the periphery of the trunk. A ratio of
residual wall thickness to the radius (t/R) of 0.3 is given as a rough guideline for safety, for
tall trees with a full canopy exposed to wind-loading [Mattheck, Bethge and Weber, 2015].
Beech T1
The circumference of Beech T1 at the position of the test was 3880mm. The diameter
calculates as 123.5cm [C= πd]. The one-third radius safety margin calculates as 20.56cm.
Tests #1 and #3 encountered advanced decay/cavity at 17.3cm and 18.9cm drilling depth
respectively. Tests #2 and #4 encountered advanced decay/cavity at 30cm and 30.7cm
respectively. Test #5 was made at 10cm height and encountered advanced decay/cavity at
25.7cm. The Resistograph drills confirm a decay cavity is developing in the centre of the
trunk and that the 1/3R safety margin has been breached at Tests #1 and #3. Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 8 of 36
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
4.1 Analysis of IML PD-400 Resistograph drillings (continued)
Beech T8
The diameter of the north-east stem of Beech T8 at 4m height was 70cm. The one-third
radius safety margin calculates as 11.67cm. Test #6 indicated that the drilling needle
encountered sound wood until 24.1cm, before the needle automatically retracted when
constant pressure on the handle was interrupted. Test #7 indicated that the drilling needle
encountered sound wood until 30.7cm, before the needle automatically retracted when
constant pressure on the handle was interrupted. Test #8 indicated that the drilling needle
encountered sound wood until encountering advanced decay/cavity at 35.1cm. The 1/3R
safety margin remains intact at all three test positions at this time.
5.0 CONCLUSIONS
Beech T1
The SoT shows a central cavity developing across the base of the trunk. The wide transition
zone between solid wood (brown) and decayed wood (green, violet and blue) indicates a
weak defensive barrier in the wood. The fungal decay is likely to increase in intensity and
extent over the next few years. The Resistograph drillings all encountered advanced
decay/cavity and the results confirm the 1/3R safety margin has been breached at MP2 and
MP7. The conclusion is that Beech T1 is in a critical condition and there is an increasingly
high risk to vehicles and pedestrians on the adjacent Bangor Road.
Beech T8
The Resistograph drillings confirm the 1/3R safety margin remains intact. The conclusion is
the tree is safe to retain at this time.
Beech T9
The SoT shows an open cavity on the east of the trunk at MP9-10. There is a narrow
transition zone between solid wood and decay, indicating a strong defensive barrier in the
wood. There is solid healthy wood around the rest of the trunk periphery and the 1/3R safety
margin remains intact. The conclusion is the tree is safe to retain at this time.
6.0 RECOMMENDATIONS
The recommendation for Beech T1 is to section-fell to ground level for safety reasons.
The recommendation for Beech T8 and T9 is to crown reduce by 25%, by shortening the
branches back by 2-3m to a suitable lateral branch.
The work should be carried out by a qualified and insured arborist to comply with BS3998
(2010) ‘Recommendations for Tree Work’.
Report written and compiled by
Stephen Cutmore BSc (Hons), MArborA,
I.S.A. Certified Arborist UI-0343A, I.S.A. Tree Risk Assessment Qualified
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 9 of 36
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 1 – Site plan (to scale)
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 10 of 36
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 2 – Picus Sonic Tomograph
Plate 1: Sonic tomograph of Beech T1 at 20cm.
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 11 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 2 – Picus Sonic Tomograph
Plate 2: Sonic tomograph of Beech T9 at 10cm.
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 12 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 3 – IML PD400 Resistograph drillings
Plate 3: Resistograph test Beech T1 #1
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 13 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 3 – IML PD400 Resistograph drillings
Plate 4: Resistograph test Beech T1#2
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 14 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 4 – IML PD400 Resistograph drillings
Plate 5: Resistograph test Beech T1#3
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 15 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 4 – IML PD400 Resistograph drillings
Plate 6: Resistograph test Beech T1#4
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 16 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 4 – IML PD400 Resistograph drillings
Plate 7: Resistograph test Beech T1#5
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 17 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 4 – IML PD400 Resistograph drillings
Plate 8: Resistograph test Beech T8#6
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 18 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 4 – IML PD400 Resistograph drillings
Plate 9: Resistograph test Beech T8#7
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 19 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 4 – IML PD400 Resistograph drillings
Plate 10: Resistograph test Beech T8#8
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 20 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 5 – Photographs
Photo 1: Basal cavity in Beech T1.
Photo 2: North-east stem of Beech T8, showing Resistograph test locations.
Photo 3: Basal cavity in Beech T9.
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 21 of 22
21 Maes-y-Dre, Ruthin, Denbighshire. LL15 1DB
Email: treevival@gmail.com
Mobile: 07877120981 Tel: 01824 709650
APPENDIX 6 – Bibliography
The following publications were referred to in preparing this report.
Lonsdale, D (1999). Principles of Tree Hazard Assessment and Management. Research for
Amenity Trees No.4. HMSO, London, UK.
Mattheck, C., Bethge, K. and Weber, K. (2015). The Body Language of Trees. Encyclopedia
of Visual Tree Assessment. K.S Druck, Kronau, Germany.
Mattheck, C. and Breloer, H. (1994). The Body Language of Trees. A Handbook for Failure
Analysis. HMSO, London, UK.
Schwarze, F.W.M.R (2008). Diagnosis and Prognosis of the Development of Wood Decay in
Urban Trees. Enspec, Rowville, Australia.
Client: Kyra Beguiristan Picus Tree Report 24 April 2017
Ref: 042017/ATI/KB Bangor Road, Caernarfon page 22 of 22